A.Maselli & 57 others: GRB 130427A: A Nearby Ordinary Monster, http://www.sciencemag.org/content/early/2013/11/20/science.1242279.abstract claims "long duration gamma bursts" come from large-star collapses and in this case immediately followed by a supernova. This event on 27 april 2013 was the brightest gamma flash ever seen at 3*10^46 watts. It was 4 billion light years away. Optical glow was detected by human observers 20 minutes after the gamma pulse (or perhaps less, but anyway there was a guy optically seeing it starting at 20 minutes). NASA's "swift" satellite detected the burst (as it does for 100 bursts/year) It relays a 3 arcminute position estimate to the ground within 20 seconds of the initial detection. It also then slews over to observe the burst with Xray and UV+optical telescopes, but this slewing takes 90 seconds. In this particular case it took 140 seconds to get the Xray telescope to see it and 147 for the UV/optical telescope. These then can provide more accurate position estimates on the order of 0.5 to 5 arcseconds, in this case 5. http://swift.gsfc.nasa.gov/about_swift/ Several gamma bursts seen by swift have been over 13 billion light years distant (based on optical red shifts) e.g. http://en.wikipedia.org/wiki/GRB_090423 which had gammas lasting 10 sec. Swift on this one failed to see it in the optical despite trying starting 77 sec later. But optically it was seen in the infrared 21 min later using ground based telescope in Hawaii. GRB080913 was also 13 GLyr away http://www.nasa.gov/mission_pages/swift/bursts/farthest_grb.html and was seen "in less than 2 minutes" by swift in the Xrays, and then after 1 further minute it was seen by ground based telescopes. The short gamma bursts appear due to mergers of compact objects (e.g. neutron stars). -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)